Processing of silver halide photographic materials, in general, comprises a development step and a desilvering step. In the processing of color photographic materials, during the desilvering step, a developed silver which has been formed in the color development step is oxidized (bleached) with a bleaching agent having an oxidizing ability to form a silver salt, and is removed from the light-sensitive layer by a fixing agent to form a soluble silver together with an unused silver halide (fixing).
There are two cases where bleaching and fixing are carried out, one is independently carried out in a bleaching step and a fixing step, the other is carried out simultaneously in a bleach-fixing in one step. Details of these processing steps are described in James, The theory of Photographic Process, 4th Edition (1977).
The above processing steps are generally carried out using an automatic processor. With the recent increase of a small in-store processing service systems known as mini-labs, rapid services for customers have been widely spread.
A work load for these mini-labs is large in, such as the preparation of processing solutions or waste disposal, therefore, it has been desired to reduce an amount of used processing solutions, that is, lower amount of replenishers.
Under the circumstances, there has recently been a great demand particularly for a rapid processing and a reduction of replenishing; and a reduction of replenishing in the bleaching, fixing and bleach-fixing steps, as well as processing with rapidity are also strongly desired.
Thiosulfate compounds have been conventionally widely used as a fixing agent in the fixing step, but various other fixing agents have been investigated. For example, mesoionic compounds disclosed in JP-A-4-143755 and JP-A-4-143756 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application"), compounds such as 3,6-dithia-1,8-octanediol, ethylene-bis(thioglycolic acid), and thiocyanic acid disclosed in Haist, Modern Photographic Processing, Vol. 2 (1979), pages 580 to 584, as a fixing agent or a fixing accelerator were proposed.
However, these compound have not practically been used due to an insufficient fixing speed, an unacceptable solubility, or a problem in safety.
A reduction in a fixing speed or an increase in a minimum cyan density (cyan stain) have been encountered due to an effect of a silver ion or a halogen ion, dissolved from a photographic material, particularly when a replenishing rate of a fixing solution is low. Thus, a reduced replenishment and a rapid processing are considered as being difficult to be compatible with.
In recent years, reducing ammonium ions from the processing solution having a fixing ability has been proposed from the viewpoint of environmental conservation, however, such a processing solution causes problems lowering the processing speed and increasing the cyan stain as well.